Not Applicable
The present invention relates to hand trucks for transporting loads, such as goods contained in a box; and more particularly to such transporting devices that include a mechanism for pushing the load off of the hand truck.
Hand trucks have been adapted in various ways to facilitate the carrying of loads. A typical hand truck design includes a frame with an axle at a lower end with a pair of wheels mounted on the axle. The lower end of the frame also has a bed or platform attached thereto onto which the load is positioned during transport. The upper end has either handles or at least an area designed for grasping by the user.
To use the hand truck of this type, the user positions it adjacent to the load with the platform against the floor on which the load is located. The hand truck then is pushed toward the load so that the platform slides under the load. In most cases, the load has to be tilted by hand so that the platform is able to slide thereunder. A second person may be required to tilt the load while the first person moves the hand truck.
Once the load is on the platform, the hand truck is tilted about the axle by pulling the upper end away from the load while the wheels are maintained relatively stationary. This action causes the platform to lift the load off the floor and back against the tilted frame of the hand truck. The hand truck and its load then are pulled or pushed along the floor.
To unload the hand truck, the frame is lowered so that the platform again rests on the floor. Then the hand truck is pulled away from the load so that the platform slides out from under the load. A second person may also be necessary to tilt the load while the first person moves the hand truck. In other cases, the user has to carry the load off of the platform.
One particularly useful method for unloading a hand truck is to pivot the platform, and allow the load to slip off, such as described in U.S. Pat. No. 5,256,025. This particular improvement over the prior has proven successful in many applications. However, in certain situations, such as when the load is heavy and does not slide easily, additional efforts to unload the load are required.
Unload mechanisms, such as disclosed in U.S. Pat. Nos. 2,682,348; 5,290,051; and 5,624,224, push a load off of a fixed platform. These mechanisms require the user to release the hand truck handle to operate the unload mechanism or to step on a lever which can result in a loss of control of the hand truck if the load unexpectedly moves off of the platform. Furthermore, if the above unload mechanisms are used with a platform, the mechanism may engage a load above the load center of gravity causing it to tip.
The present invention provides a hand truck for transporting a load. The hand truck includes a frame having an upper portion and a lower portion, and a cargo support pivotally attached to the lower portion of the frame. A pair of wheels are rotatably connected to the frame, and an unload mechanism having a latched position and an unlatched position is pivotally coupled to the cargo support and the frame. In the unlatched position, pulling the upper portion of the frame rearward causes the unload mechanism to urge the load off of the cargo support.
In one aspect of the invention, the unload mechanism includes a linkage mechanism pivotally coupled to the frame which urges a pusher plate against the load to urge the load off of the platform.
In another aspect of the present invention the unload mechanism includes a linkage mechanism having a push arm pivotally coupled to a pusher plate and a push end of a rocker arm. The rocker arm is pivotally mounted to the cargo support, and has a pull end pivotally coupled to one end of a pull arm. The opposing end of the pull arm is pivotally coupled to the hand truck frame, wherein pulling on the hand truck frame pulls on the pull arm which pivots the rocker arm to push the push arm to urge the pusher plate against the load.
A general objective of the present invention is to provide a hand truck unload mechanism to assist a user to remove a load from the hand truck. This objective is a accomplished by providing a pusher plate linked to the hand truck frame that urges the load off of the platform.
Another object of the present invention is to provide a hand truck mechanism which is operable while maintaining control of the hand truck during the unload operation. This objective is accomplished by providing an unload mechanism which is operated by pulling back on the hand truck handle.
These and still other objects and advantages of the present invention will be apparent from the description which follows. In the detailed description below, preferred embodiments of the invention will be described in reference to the accompanying drawings. These embodiments do not represent the full scope of the invention. Rather the invention may be employed in other embodiments. Reference should therefore be made to the claims herein for interpreting the breadth of the invention.